How to change the status field of a foreigner every 3 months and send an alert [closed]

I have no idea how to do this. I have a view with two tables, where one shows me the status of a team and the other the maintenance that is done to them, what I want to do is change the status of "pending" made when maintenance is done and every 3 months change only for slope and send an alert saying that maintenance has to be done. I hope you can help me.

<div class="container">
<div class="row">
    <div class="panel-heading" align="center"><h2 class="page-header" align="center">MANTENIMIENTO</h2></div>            
    <div class="panel-body">                                    
        <a href="{{route('mantenimiento_imp.create') }}" class="btn btn-info btn-block"  >Nuevo Mantenimiento</a>
    </div>              
    <table width="100%" class="table table-striped table-bordered table-hover" id="dataTables-example">
        <thead>
            <tr>
                <th>ID PC</th>
                <th>Motivo</th>
                <th>Diagnostico</th>
                <th>Ver</th>
                <th>Editar</th>
                <th>Eliminar</th>
            </tr>               
        </thead>
        <tbody>
            @if($mantenimientos_imp->count())
            @foreach($mantenimientos_imp as $mantenimiento_imp)  
            <tr>
                <td>{{$mantenimiento_imp->impresora_id}}</td>
                <td>{{$mantenimiento_imp->motivo}}</td>
                <td>{{$mantenimiento_imp->diagnostico}}</td>
                <td><a class="btn btn-success btn-xs" href="{{route ('mantenimiento_imp.show',  $mantenimiento_imp->id)}}"><span class="glyphicon glyphicon-eye-open"></span></a></td>
                <td><a class="btn btn-primary btn-xs" href="{{action('Mantenimiento_impController@edit', $mantenimiento_imp->id)}}" ><span class="glyphicon glyphicon-pencil"></span></a></td>
                <td>
                    <form action="{{action('Mantenimiento_impController@destroy', $mantenimiento_imp->id)}}" method="post">
                        {{csrf_field()}}
                        <input name="_method" type="hidden" value="DELETE">

                        <button class="btn btn-danger btn-xs" type="submit" onclick="return confirm('Esta seguro de Eliminar el Registro?')"><span class="glyphicon glyphicon-trash"></span></button>
                    </form>
                </td>
            </tr>
            @endforeach
        </tbody>       
    </table>

</div>
<?php
$mes = substr($mantenimientos_imp->fecha_mant, 3, 1);
$dia = substr($mantenimientos_imp->fecha_mant, 1, 1);

$f = date("d-m-Y");

$mes_act = substr($f, 2, 2);

$ret = DB::table('mantenimientos_imp')->select('fecha_mant')
        ->where($mes, '<', (int) $mes + 3);
if ($ret != NULL) {
    echo "Hagale mantenimiento";
} else {
    echo "estamos bien";
}
?>
<div class="panel-heading" align="center"><h2 class="page-header" align="center">Impresoras pendiente de Mantenimiento</h2></div>  
<table width="100%" class="table table-striped table-bordered table-hover">
    <thead>
        <tr>

            <th>Nombre</th>
            <th>Marca</th>
            <th>Estado</th>

        </tr>               
    </thead>
    <tbody>
        @foreach($impresora as $impresoras)  
        <tr>
            @if($impresoras->estado == 'Pendiente')
            <td>{{$impresoras->nombre_imp}}</td>

            <td>{{$impresoras->marca_imp}}</td>

            <td class="label-danger">{{ $impresoras->estado}}</td>
            @endif
        </tr>
        @endforeach
    </tbody>           
</table>